The total annual global electricity consumption by the telecom industry has been estimated at 164 billion kWh. In the USA alone, the Verizon 2006 network consumes 8.9 TWh, 0.24% of the USA's total energy consumption. This presents a problem.
Many data protocols send high energy patterns when there is no data to transmit. For example, the HDLC (High-Level Data Link Control) protocol used in the Ethernet MAC (Media Access Control) layer uses the pattern 01111110 to indicate idle periods between frames of data. This decreases average energy efficiency because more energy is used to transmit idle patterns than data patterns. Networks transport data with low link utilization, 80% idle is not unusual. True zeroes cannot be used during idle periods because transition to and from loss of signal states is generally integrated over periods of between 10 and 255 UI with 1 UI having a period of 488 us in E1 mode and 648 ns in T1 mode. This LOS (Loss Of Signal) detection and clearing delay is too long and would disrupt normal transmission. This presents a problem.
Previous efforts at lowering power include powering down the transmitter for a link during idle periods and deferring transmission to lengthen idle periods and make the average efficiency higher, however, they do not deal with maintaining synchronization over the link or dealing with non-idle-state periodic high energy data patterns such as idle data generated remotely and being transported by the link. This presents a problem.
Another previous effort is with ADSL2 and ADSL2+ in which states L2 and L3 were conceived to offer degraded performance but lower power states together with a method for switching between them. This presents a problem.
Thus there is a need for a technical solution to this technical problem that does not conceive any degradation of transmission performance.